Diagnosing Degenerative Disc Disease

Physicians and surgeons who specialize in conditions affecting the spine collaborate at NYU Langone’s Spine Center and the Endoscopic Spine Surgery Program to diagnose degenerative disc disease. The thick, spongy discs of cartilage that lie between vertebrae— the bones of the spine—help to absorb the weight of the body during movement and stabilize the spine by maintaining even spaces between the bones. In degenerative disc disease, these discs of cartilage gradually deteriorate.

This degeneration can occur over time as a result of the accumulated stress of everyday movements. Each disc is composed of a tough outer wall surrounding a soft inner core composed of a hydrating gel-like substance. As you age, the discs may dry out and become less resilient.

If the discs lose fluid and shrink, the spaces between the vertebrae become smaller, which may eventually lead to abnormal movement between the vertebrae. It may also cause bony growths, called osteophytes, to form. In some instances, these growths encroach on the spinal canal, narrowing the space through which the spinal cord and nerves pass. This is called spinal stenosis.

Age-related changes in the discs may also lead to small tears in their outer walls. If the wall breaks down, the inner core may push through the cracks, causing the disc to bulge or move into the spinal canal, the bony cavity that protects the spinal cord and nerves. This is called a “slipped disc,” or herniated disc.

Disc degeneration is often associated with osteoarthritis of the spine, the progressive erosion of cartilage that lines the ends of the bones in the spinal joints. In a healthy spine, the facet joints—which are located behind the vertebrae and discs—move smoothly against each other, allowing the spine to bend and twist. If the protective layers of cartilage erode, movement between them can become painful and lead to permanent joint damage. A narrowed disc space may put increased pressure on the spine’s joints, starting the degenerative process.

Symptoms

Symptoms of degenerative disc disease vary based on whether changes in the size or position of the discs cause anatomical changes in the spine. For many people, a narrowed disc space alone may not cause any symptoms. Others may experience a persistent ache in the back or neck that worsens during long periods of sitting or standing or when they bend or twist.

If a disc bulges or slips out of place into the spinal canal, it may put pressure on nerves or the spinal cord. Compression can lead to tingling, numbness, or pain, which may radiate to the legs or arms.

Doctors at NYU Langone diagnose degenerative disc disease by evaluating your symptoms and conducting a physical exam. Often, they recommend imaging tests to identify the cause of back or neck pain and determine how much of the area surrounding the disc is affected.

Medical History

Your doctor asks you a variety of questions about your symptoms and medical history, including when you first noticed pain and stiffness; which part of the spine hurts; whether you feel pain, tingling, or numbness in the arms or legs; and how much symptoms interfere with your everyday activities. You may also discuss whether you’ve had any spine injuries, which may contribute to the development of degenerative disc disease.

Physical Exam

Doctors examine your spine for signs of degenerative disc disease, including pain or tenderness in the neck or lower back, as well as evaluate the spine’s flexibility and range of motion. Doctors may ask you to walk or bend so they can assess what motions are most painful and whether pain and stiffness significantly affect movement. If these movements cause tingling, numbness, or weakness in the arms or legs, doctors may recommend further testing to determine if any nerves are affected.

X-ray

Your doctor may recommend taking an X-ray to examine the vertebrae of the spine. X-rays can reveal reduced height between vertebrae, bone spurs, or a vertebra that has slipped out of place.

A flexion-extension X-ray is taken while you bend forward and backward. Compared with a traditional X-ray, flexion-extension X-rays give your doctor more information about movement between vertebrae.

Your doctor may also order a three-foot standing X-ray, which involves taking images of the front and back of your spine, called anterior-posterior X-rays; or of each side, which are called lateral X-rays. These images are referred to as “three-foot” because the X-ray film is large. They provide details about spinal alignment, which may be affected by degenerative disc disease.

CT Scan

CT scans combine a series of X-rays to provide two- and three-dimensional images of the spine from a variety of angles. CT scans may reveal structural changes in the spine in more detail than a regular X-ray. Our doctors and radiologists use CT technology with the least amount of radiation possible.

MRI Scan

An MRI scan uses magnetic fields and radio waves to create detailed two- and three-dimensional images of the discs as well as the nerves and spinal cord, which pass through the spinal canal. Doctors examine MRI scans for evidence of disc degeneration and to determine if any nerves are pinched between bones.

Electromyogram

If pain radiates to your arms or legs—or you experience any weakness, tingling, or numbness—an electromyogram can reveal whether nerves are being pinched as a result of a disc that has slipped out of place.

An electromyogram measures the electrical impulse transmitted along nerves, nerve roots, and muscle tissue. This test helps doctors to determine if pain or weakness originates in the muscles or nerves. If pain originates in the nerves, it may indicate that a herniated disc is compressing a nerve or part of the spinal cord.

During this test, your doctor inserts small, thin needles, called electrodes, through the skin and into muscles that correspond to specific nerves and then asks you to move these muscles one at a time. The signals record when each muscle contracts and can indicate which nerve roots are affected and whether a nerve injury has caused muscle damage.

An electromyogram is relatively painless, though some people are uncomfortable with the needles. Usually, the test takes about 15 to 30 minutes to complete.